1. Field of the Invention
The present invention relates to a paper supply tray used for a printer such as a laser printer or a photocopier.
2. Description of the Related Art
As shown in FIG. 1, a typical printer includes a paper supply tray for receiving sheets of paper or other printable material and conveying the received sheets to a printer body 10. The paper supply tray includes a main body 20 in which sheets are received, a pair of side guides 21 and 22 supporting the side edges of the received sheet, slidably installed in the main body 20, and a top guide 23 supporting top edges of sheets. Reference numeral 24 indicates a finger member compressing and supporting a corner portion of bottom edges of the received sheets, and reference numeral 25 indicates a settling plate elastically-biasing the received sheets towards the finger member 24.
Here, as shown in FIG. 2, the side guides 21 and 22 interlock with a pinion 27 rotatably installed at the bottom of the main body 20. Also, a locking protrusion 22a' formed at an elastic piece 22a of each of the side guides 21 and 22 is elastically engaged with a locking groove 28a formed in a guide rail 28, to thereby adjust the position thereof in accordance with the size of the sheet.
Also, as shown in FIG. 3, the position of the top guide 23 is predetermined by connecting a teethed portion 29 of the main body 20 to a connection piece 23a. Thus, sheets are received in the main body 20, and then the side guides 21 and 22 and the top guide 23 are adjusted in accordance with the paper size, such that the locking protrusion 22a' and the locking groove 28a, and the teethed portion 29 and the connection piece 23a are locked, respectively.
However, when sheets are received in the main body 20, and then the paper supply tray is inserted into the printer body 10 (FIG. 1), the locking of the locking protrusion 22a' and the locking groove 28a, and the teethed portion 29 and the connection piece 23a may become disengaged due to connection shock or the inertial force of the sheet. With a larger number of received sheets, the locking may more easily become disengaged. When the locking of the guides 21, 22 and 23 are disengaged, the sheets may become jammed in the printer, so that the supply of a sheet or printing cannot be operated normally.